Based on these information, it is reasonable to hypothesize the following mechanism in the pathogenesis of pterygium that UV-B irradiation causes the activation of the NF-KB signaling pathway and the expression of COX-2 and VEGF elevating, the higher levels of COX-2 and VEGF could cause the angiogenesis, and then lead to pterygium. This evidence concerns the gene PTGS2 and pterygium.